Continuous inductive train-control system



March 3, 1931. w. HAILES 1,794,608

I CONTINUOUS INDUCTIVE TRAIN CONTROL SYSTEM Filed July 18, 1929 Patented Mar. 3, 1931 mm srATi-is OFFICE.

WILLIAM n. HAILES, or nocnns'rnn, NEW YORK, 5mm: moennnnan RAILWAY SIGNAL comm s, or. ROCHESTER, NEW 'YoRK CONTINUOUS I NDUc rivE Application filed July s,

This invention relates in general toelectric filters, and has more particular referenceto a filter foruse in continuous inductive alternating current'train control systems, either of the uncoded type, or ofthe coded type, such as disclosed in] the application of \V. D. Hailes, SenNo. 228,058, filed October 22, 1927, for Continuous train control systems. p

In train control systems of the type refcrredto, it is usual to employ alternating train control current ofa frequency. different from the usual commercial frequencies, suchfor example as 100 cycles per second, wherebyto avoid interference, by currentsofother frequencies with the car-carried receiving apparatus. Also, in order-to insure against such interference, a filter circuit can'be employed in connection with the'receiving car-carried apparatus for filtering outorsuppressing, or both,cr 1rre nts of other than train control frequency. a 1 V In connection with coded continuous systems, it is desirable to have means for preventing oscillations produced by the coded 1 current in the receiving apparatus and con- H systems.

diagrammatic manner, and in no manner ina limiting sense, one form which the invention can assume. ,Inthe drawing The-single figureof drawing isa diagrammatic representation of a. filter circuit in ac- '3 cordance with the present invention;

, Referring to the drawing, there a is here shown a pair of track rails 1, through which train control currents flow as'indicated by thearrows 2,- with car-carried receiving coils 13cc positioned above, and in inductive .rela- TRAIN-CONTROL sYs'rEM' 1929. Serial m 379,34.

tion to, the rails, whereby to have voltages in- 'theprirnary having a plurality oftaps a, I), 0

and d whereby to permit varying the number of turns in the primary. winding at will.

The circuit connecting up the receiving coils with the primary of transformer T in clude's, in series, the two receiving coilsRca,

a resistance R, a resistancelt the primary;

P of the transformer T, a choke coil X,

condenser C and a condenser C The constants of this circuit have been chosen so nation thancurrents of either higher'or lower frequencies. By this choice of constants the circuit acts so -as to permit relatively large currents of 100 cycles-to flowthroughfhe primary of transformer ,T, and to permit only relatively small currents of frequencies other than 100 cycles to flow through the primary of transformer T. Hence when the receivers Y are excited by 100 cycle currentthis circuit passes 100 cycle exciting current on to the transformer T; when receivers are excited by currents of other thanlOO cycles this circuit alternates the currents transmitted to'thc transformer, and, when 100 cycle and also otherfreqnency cifirrentsare present under the receivers this circuit automatically passes on the 100 cycle current and alternates the currents ofthe other frequencies.

Since only 100 cycle 'currentis perinittedto flow to any great extent in the primary of transformer T the only voltage generated to any great extent in the secondary of transformer T will be of 100 cycles; Also since there is loose coupling between primaryand secondary of transformenT, the small v'ol-tages other than 100 cycles will be .unable to produce-any appreciable current in the secondary, but the 100 cycle voltage generated in thel'secondary will cause a large secondary 'current because C" is adjusted to enhance the effect offlOO cycle voltage and to diminish the effects .of other voltages. Therefore'the 1 effect of 100 cycle railcurrent isto. produce to pass currents of 1Q0'cycles with less alter- 7 a relatively large 100 cycle voltage across the condenser C" and the effect of currents of other than 100 cycles is alternated so greatly as to be negligible.

1 The secondary S of transformer T is connected in series with a resistance R across a condenser C to "constitute aascircuit tuned to resonance at the frequency of the traincom trol current and including inseries the secondai'y S, the resistance R-"-*and the condenpath coupling the primary and secondary turns, or by having the primary turns-relatively few ,with respect to the secondary turns'ona good magneticcircuit, or both. In this inan-ner, the voltage'across the second ,ary winding -S can beadjusted by adjusting the number of turnsincluded in the pri .ma'ry winding. Due, to the loose, coupling, if thenumber of turns in the (primary nding be increased, theivoltage'across the seconldary Windinglikewiseincreases.;.

In the filter circuit just-described, it "was found'desirable to make, the inductance of the choke'coil X approximately equal to the inductance of the two receiving coils Bee in er es..,. a 1' 1 The loose coupled transformer, T is employed'tovprovide additional selectivezability in the apparatus and provide-a ready. means of controlling the overallrsensitivity of the complete circuit, and to deliver. the filtered receiver energyto the ;amp'l i fie'r at; a suitable voltage, This control isv accomplished by means of-the primary having the severaltaps asdcscribed above, and the additional selec- --tivity is obtainedby virtue of the condenser C' which-is adjustethas set forth above, so that, for the desired frequency, maximum voltage appears at theterni'inals of the transformerseconda'ry. S.

The resistances R R? and are 'not required for filtering action but are used for the purpose of fixingv the rate at which oscillations set up in the circuits will die out on removal of excitation, andare useful where the filter is tooperate as apart of a coded type f ntro1-, such as described ;in the Hailes application above referred to. Rather than including these resistances in the receiving. coils Rec, they 1&18 constituted by separate units which can be inserted-or removed as required, the receiving coils bein'g'madeso =as to'include no unnecessary resistance.

In this manner the filter circuit minus the various resistances R etc., can be employed to advantage in connection with uncoded systems, While the circuit as shown can be employed in connection with coded I systems, with the receiving coils Rec the same in each-case. g v

The above rather specific description of ,oneform of device embodying the present invention has been given sole.y by way of illustration,and is not intendethi'n any manner whatsoever, in 'ali'miting sense. Obviously, this invention can assume many different physical forins,"and is susceptible of numerous modifications, and all such forms and modifications are desired to be included by this invention, as comewit'hin the scope of the appended claims.

-Having described my invention, I now claim 1; In afilter circuit for use in train control systems, in combination, a receiving coil, "a loose-coupled transformer, a series cir-- cuit connecting the primary of the transfo-rmerfto the receiving coil and including tuning means for tuninglthe circuit to resonance at a desired frequency, a condenser connected across .the secondary of the transformer for tuning the circuit including the secondary andthe condenser to resonance at the desired frequency,.a shunt connection across the receiving coil forshunting-other than the desired frequency around the primary of thetransforn'ier, and resistance in% ,sertablein the primaryand the secondary tuned circuits for adjusting the-rateofdecay of oscillations after excitation has ceased, for adapting'the filter for-usein coded tr'ain control systems. 7 r i 2. In asfilter circuit for use intrain control systems, in combination, a receiving coil, a loose coupledtransformer, a series circuit connecting the primary of the transformer 'tothe receiving coiland including tuning means for tuning the'circu'it to resonance ata desired frequency, a condenserfconnected across the secondary of the transformer for tuning the circuit including the secondary and the condenser to resonance at the desired frequency, a shunt connection across the receiving coil for shunting otherthan the desired frequency around the primary of the transformer, and a plurality; of taps on the primary ofthe-transformer Wherebyfto permit adjus'ting'the ratio ofpri-mary to seconda'ry turns "for adjustingtha o-verall'sensitivity ofthejfilterljand the voltage across the transformer secondary. i

3. In a filter circuit 'for use in trainjcontrol systems, in" combination, a receiving coil, a loose "coupled transformer, "a'cir'cuit connecting the primary of the transformer to *the receiving coil and including'tu'ning means for tuning the circuit to resonance'at a desired frequency, a condenser connected across the secondary of the transformer for tuning the circuit including the secondary and the condenser to resonance at the desired frequency, a shunt connection across the receiving coil for shunting other than the desired frequency around said primary of the transformer, resistance means insertable in the primary and secondary tuned circuits for adjusting the rate of decay of oscillations after excitation has ceased, for adapting the filter for use in coded train control systems, and a plurality of ta s on theprimary of the trans- -former Where y the permit adjusting the ratio of primary to secondary turns for adjusting the overall sensitivity of the filter and the voltage across the transformer secondary. In testimony whereof I aflix my signature.

WILLIAM D.. HAILES. 

